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RESEARCH

KEYWORDS:

Behavioural ecology / Animal colouration / Animal communication / Colour change

NEWS:

 

    New paper about F. Pardalis color change is now online

  

   Turkey team on fire ! Check "turkey team" for pictures and few update

Alexis Y. DOLLION (handling a brown water snake in South-Africa)
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BIOGRAPHY of Alexis Y. DOLLION:

Dr. Dollion’s research generally focuses on animal colouration and its role in communication, with an interest in rapid colour change. Rapid colour change allows animals to quickly become more or less conspicuous depending on the environmental context, and some use this feature to communicate. Nevertheless, at present, we poorly understand the function, contexts, information content, and evolutionary history of rapid colour change in most animals. These knowledge gaps for rapid colour change may be due, in part, to the technological and methodological challenges associated with quantifying such a dynamic trait. However, recent advances in colour quantification - multispectral and hyperspectral imaging and animal visual systems modelling- enable rigorous, non-invasive analyses of rapid colour change as it perceived by animals(i.e. conspecific rivals/mates or heterospecifics like predators).

The study of rapid colour change in animals is an emerging area of science, and Dr. Dollion is fully dedicated promoting interdisciplinarity and developing new methodologies in this domain and pushing further the knowledge boundaries of animal communication. Through his academic curriculum, Dr. Dollion acquired a broad background and expertise in behavioural ecology, evolutionary biology, animal biology, animal physiology and animal colouration.

During his PhD, Dr. Dollion studied the evolution of rapid colour change in chameleons and its role in sexual selection, using panther chameleons (Furcifer pardalis) as a biological model.

Thanks to his PhD, Dr. Dollion acquired a broad skill set and insights into animal colour change which can be leveraged to further enrich this emerging area, including in other taxa like birds. After, a quick stop at Université de Lille where he worked at as in ingeneer in experimental zoology, Dr. Dollion a Fyssen postdoctoral fellowship to work in Arizona State University where he investigated the role of rapid colour change in the wild turkey (Meleagris gallopavo). Thanks to my incredible student team (the turkey team) we gathered a plethora of data on turkey's physiology and behaviors, that we are analyzing. So far we found that the agressiveness of the turkey toms is related to some physiological parameters and matching patterns found in literature about other species. Our primary observation of their behavior suggest an involvement of their head color change in social interaction. STAY TUNE for the coming publications about it.

After a 2 years stay in Arizona, he came to France to start a new position as a lecturer in animal behavior and neurosciences.

On-contract lecturer at Université de Rennes (Rennes, France)

Smmary: Since September 2023 I am working as lecturer (on-contract) at Université de Rennes where I teach to undergrads various classes related to neurosciences and animal behaviors within the department (UFR) of "life sciences and environmental sciences" (SVE: sciences de la vie et de l'environnement). At Université de Rennes, in term of research, I joined the ETHOS lab and more precisely the team DEEP (Deleopment & plasticity: parental effects). The research project is still to be determined but I likely work on the physiological aspect of positive emotions in the european qual (Coturnix coturnix) and the potential "expression" of this emotion through color change (flushing).

 PostDoc the RACCHIT Project: "Role of rapid color change in turkey's communication"

Abstract: Various species of birds use colourful ornamements to communicate. To this regards, most of the studies on color communication in birds, focuses on plumage and feather, and rarely on bare skin parts like the caruncle or ceres. However, those bare parts are actually very interesting as their coloration can varies according to their physiological state as shown in some studies. So far, the studied color changes took days to occurss, but and surprinsigly some species of birds are capable of exhibiting rapid color changes, as dynamic as those of chameleons! One of those species is the turkey (Meleagris gallopavo). Eventhough the turkey is common in the poutlry, nealry nothing is actually known about its color change ability: mechanism or function. In this project, we aim to uncover the function of the color change of turkeys. Because in color changing species, like the chameleons, color change as been shown to be use as a communication media, we assumed that turkeys would also use it to communicate. This hypothesis is even more supported as breeders mentionned observing turkey toms color changing while courting or competing. To investigate whether turkey use color change to communicate, we set behavioral trials during which we recorded their behavior and took pictures every 6 seconds to analyse their color change taking into accoung their vision. We first analyzed the link between the observed behaviors and the color change to show wether color change modify the behavior of the receiver, and thus is use to communicate. And on an other hand, we collected blood before and after each trials to analyze various physiological parameters and see whether those could correlate with the observed color change to decipher the potential information content of the turkey's color change.

Ph.D the COCOON Project: "Color change origins of new species ? The chameleon case"

The COCOON project logo
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Abstract: Colour change is not as unusual as often thought. Although the mechanisms allowing colour change are currently largely understood, the evolution of this intriguing ability remains poorly investigated. In chameleons, there is some support for the “selection for social signalling” hypothesis. However, in chameleons, one prediction which states that there should be “More intense sexual selection” remains to be tested. Moreover, the evolution of chameleon colour change has only been investigated at the genus level while the entire family is capable of changing colour. The aims of this thesis are to better understand the evolution of colour change and the evolution thereof. I approach this topic through two main lines of research. First, I investigated the role of colour change in sexual selection in the panther chameleon through an integrative approach combining physiological and performance measurements, behavioural experiments, and colour analysis. Second, I studied the evolution of colour change within Chamaeleonidae. I traced the evolution of colour change using a comparative phylogenetic analysis and explored some of the selective pressures thought to have driven its evolution. I also briefly present preliminary results of a comparative histological analysis of chameleon skin structure, investigating whether differences in the dermal chromatophore units (DCU) are linked to differences in the ability to change colour or differences in ecology. The results of this thesis provide support for the “selection for social signalling” hypothesis. On the one hand, I showed that chameleons rely on specific aspects of colour change for sexual selection. On the other hand, the comparative phylogenetic analysis revealed that habitat shifts are a likely selective pressure acting on the evolution of the ability to change colour in some chameleon genera. Yet, changes in habitat do not explain all shifts in colour changing ability, suggesting that other selective pressures were important drivers of the evolution of colour change in chameleons. The preliminary results of the comparative histological analysis revealed that habitat is likely a selective pressure acting on the evolution of the DCU composition, mostly on the xantho-erythrophore layer. These results also show that differences in colour change ability between species could to some degree be explained by differences in DCU composition. Altogether, these results suggest that sexual selection mediated by colour change is an important driver of speciation in Chamaeleonidae.

Sexual dimorphism in F. pardalis  (picture from Olimpia Martinotti)
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